Terahertz radiation represents electromagnetic waves with frequencies in the range of 0.3 to 3 THz (100 μm to 1 mm). This frequency spectrum lies between the microwave and the optical (far Infrared) spectral bands. THz radiation is important and promising for applications such as, but not limited to, high-bandwidth communications, medical, biological and industrial imaging, the non-invasive imaging of concealed items, radar, and space science.